From: Andy Lutomirski <luto@amacapital.net>
To: unlisted-recipients:; (no To-header on input)
Cc: "H. Peter Anvin" <hpa@zytor.com>,
"Richard Weinberger" <richard@nod.at>, "X86 ML" <x86@kernel.org>,
"Eric Paris" <eparis@redhat.com>,
"Linux Kernel" <linux-kernel@vger.kernel.org>,
security@kernel.org, "Steven Rostedt" <rostedt@goodmis.org>,
"Borislav Petkov" <bp@alien8.de>,
"Toralf Förster" <toralf.foerster@gmx.de>,
"Andy Lutomirski" <luto@amacapital.net>,
stable@vger.kernel.org, "Roland McGrath" <roland@redhat.com>
Subject: [PATCH] x86_32,entry: Do syscall exit work on badsys (CVE-2014-4508)
Date: Mon, 23 Jun 2014 14:22:15 -0700 [thread overview]
Message-ID: <e09c499eade6fc321266dd6b54da7beb28d6991c.1403558229.git.luto@amacapital.net> (raw)
In-Reply-To: <CA+5PVA70nFS8JZkL0-Q-1HjFHT5NA04275_M4WstjQMrpT+hrQ@mail.gmail.com>
The bad syscall nr paths are their own incomprehensible route
through the entry control flow. Rearrange them to work just like
syscalls that return -ENOSYS.
This fixes an OOPS in the audit code when fast-path auditing is
enabled and sysenter gets a bad syscall nr (CVE-2014-4508).
This has probably been broken since Linux 2.6.27:
af0575bba0 i386 syscall audit fast-path
Cc: stable@vger.kernel.org
Cc: Roland McGrath <roland@redhat.com>
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
I realize that the syscall audit fast path and badsys code, on 32-bit
x86 no less, is possibly one of the least fun things in the kernel to
review, but this is still a real security bug and should get fixed :(
So I'm cc-ing a bunch of people and maybe someone will review it.
arch/x86/kernel/entry_32.S | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index a2a4f46..f4258a5 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -431,9 +431,10 @@ sysenter_past_esp:
jnz sysenter_audit
sysenter_do_call:
cmpl $(NR_syscalls), %eax
- jae syscall_badsys
+ jae sysenter_badsys
call *sys_call_table(,%eax,4)
movl %eax,PT_EAX(%esp)
+sysenter_after_call:
LOCKDEP_SYS_EXIT
DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
@@ -688,7 +689,12 @@ END(syscall_fault)
syscall_badsys:
movl $-ENOSYS,PT_EAX(%esp)
- jmp resume_userspace
+ jmp syscall_exit
+END(syscall_badsys)
+
+sysenter_badsys:
+ movl $-ENOSYS,PT_EAX(%esp)
+ jmp sysenter_after_call
END(syscall_badsys)
CFI_ENDPROC
/*
--
1.9.3
next prev parent reply other threads:[~2014-06-23 21:22 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-16 16:33 3.15: kernel BUG at kernel/auditsc.c:1525! Toralf Förster
2014-06-16 17:21 ` Richard Weinberger
2014-06-16 17:25 ` Andy Lutomirski
2014-06-16 17:29 ` Richard Weinberger
2014-06-16 17:32 ` Andy Lutomirski
2014-06-16 17:36 ` Toralf Förster
2014-06-16 17:50 ` Andy Lutomirski
2014-06-16 17:59 ` Toralf Förster
2014-06-16 18:15 ` Andy Lutomirski
2014-06-16 18:21 ` Toralf Förster
2014-06-16 18:24 ` Andy Lutomirski
2014-06-16 18:36 ` Toralf Förster
2014-06-16 20:41 ` Toralf Förster
2014-06-16 20:43 ` Richard Weinberger
2014-06-16 21:35 ` Andy Lutomirski
2014-06-16 21:48 ` H. Peter Anvin
2014-06-16 21:54 ` Andy Lutomirski
2014-06-16 21:58 ` H. Peter Anvin
2014-06-16 22:00 ` Andy Lutomirski
2014-06-20 15:41 ` Andy Lutomirski
2014-06-20 17:35 ` Toralf Förster
2014-06-23 21:04 ` Josh Boyer
2014-06-23 21:22 ` Andy Lutomirski [this message]
2014-06-23 22:18 ` [tip:x86/urgent] x86_32, entry: Do syscall exit work on badsys ( CVE-2014-4508) tip-bot for Andy Lutomirski
2014-06-24 10:51 ` [PATCH] x86_32,entry: Do syscall exit work on badsys (CVE-2014-4508) Borislav Petkov
2014-06-24 20:53 ` Andy Lutomirski
2014-06-24 21:18 ` Borislav Petkov
2014-07-01 10:52 ` Quentin Casasnovas
2014-07-01 14:14 ` Andy Lutomirski
2014-06-17 15:38 ` 3.15: kernel BUG at kernel/auditsc.c:1525! Toralf Förster
2014-06-17 16:19 ` Andy Lutomirski
2014-06-20 4:44 ` Fwd: " Andy Lutomirski
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